Self-adjusting guard for hacksaws.



R. S. BARNUM. lSELF ADJUSTING GUARD fron HAcKsAws.

APPLICATION FILED AUGJ. ISIB.

Patented Oct. 8, 1918.A

FFICE.

RUSSELL S. BARNUM, 0F CHICAGO, ILLINOIS.

SELF-ADJUSTING GUARD FOR HACKSAWS.

Specification of Letters Patent.

Patented Oct. 8, 1918.

Application led August 7, 1918. Serial No. 248,689.

To all whom t may concern:

Be it known that I, RUSSELL S. BARNUM, of Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Self-Adjusting Guards for Hacksaws, of which the following is a description, reference being had to the accompanying drawings, forming a part of this specification, in which corresponding numerals of reference in the different figures indicate like parts.

The difficulty of using hack-saws without breakage is well known to mechanics. .The high temper and excessive hardness of the metal render them very brittle and the unevenness of movement and lateral stresses incident to the starting of a cut, during which the hand of the operator is necessarily caused to Waver, results in an excessive breakage of blades at the very beginning of an attempt to use them.

The object of my invention is to overcome this difficulty by providing simple and effective means for reinforcing the blade and that especially while making the initial cut, and continuing such reinforcement until a sufficient kerf is formed in the metal to be cut, to constitute a guide for the sawblade,-the reinforcing means being automatically moved out of the way by Contact with the metal acted upon as the cut therein is progressively deepened. To these ends, my invention consists in the combination of elements hereinafter more particularly described and definitely pointed out in the claims.

In the drawings,

Figure 1, is an elevation of a hack-saw embodying the features of my invention with the reinforcing member or guard in position for use,

Fig. 2, is a like view showing the saw as it would appear when in use with the guard partially raised by contact with the metal being sawed,

Fig. 3, is a transverse section of the sawblade and guard taken upon the line 3--3, Fig. 1, viewed in the direction of the arrow there shown,

Fig. 4, is a section taken upon the line 4-4=, Fig. 1, viewed as indicated by the arrow, and

Fig. 5, is a side elevation of the rear portion of the guard as it would appear from the opposite side from that shown in Fig. 1.

Referring to the drawings, 1 indicates t-he usual metal frame of an ordinary hack-saw having a handle 2', partially broken away and the usual connecting members 3 and 4 at opposite ends for connecting an ordinary hack-saw blade 5 therewith by means of laterally projected pins G and 7 respectively, which are rigidly attached in a well known way to the members 3 and el. Said pins are projected as shown through the usual perforations in the ends of the saw blade when the latter may be placed under tension by means of a thumb-nut 8, upon the outer screw-threaded end of the member l; all of which is common and well known.

A guard or reinforcing member, generally designated by 9, stamped or otherwise formed from sheetanetal, has parallel walls 10, 11, the latter of which is provided with a lug or extended portion 12, having an opening 13 therein, adapted, when the guard is adjusted upon the saw-blade, to register with the opening in the rear end of the latter, so that the pin 6, will pass through both. The walls 10 and 11 are spaced apart a suflicient distance to receive the saw-blade between them with sufficient friction to hold the guard in place in the manner indicated in Figs. 1 and 3. in which the normal position of the guard is shown. This leaves the forward end of the guard free to be tilted upwardly as shown in Fig. 2 when an upwardly directed force is applied thereto as hereinafter described. y

The extent to which said guard may be raised may vary so as to cause it to pass upwardly beyond the frame if desired, there being suflicient lateral play to permit such action. In such case I preferto provide means for continuing the friction of the saw against the blade so that the former may be caused to temporarily remain in any desired raised position. A depending lug or friction-member 14, is formed upon the wall 10 at the rear end of the guard so as to normally extend below the lower edge of the saw as shown in Figs. 1, 2 and 4l. This lug is so formed as to press against the face of the saw with a 'suilicient degree of friction to hold the guard in any raised position which it may be caused to assume.

The operation of the device is as follows The guard is first placed upon the sawblade with the opening 13, in registration with the opening in the rear end of the blade. The pin 6 is then passed through the two, the pin 7 passed through the opening in the forward end of the blade and the nut S tightened, when the saw, with the guard in the position shown in Fig. 1, is ready for use. When starting to make a cut, as, for example, in a metal bar 15, Fig. 2, the lower edges of the guard are, preferably close down to the saw-teeth as shown in Fig. 1 and indicated in dotted lines in Fig. 2, which serves to stifen the blade and prevent it from kinking while starting the cut. As'soon as the cut is sufiiciently deep so as to form a Vguide in itself, the lower edges of the guard will be brought into contact with the upper face ofthe part 15 and will be slightly lifted with each forward movement of the saw without interfering with the work of the latter. rlhis may be continued until a cut of considerable depth may be formed while still maintaining the reinforcing action of the guard; yand when the cut is sufficiently deep to cause the guard to be lifted out of engagement there will remain but little if any necessity for its use, inasmuch as the critical period is that during which the cut is started. With each new operation, it follows that the guard should be returned to its normal position.

1 have shown what 1 regard as the simplest and best means of attaching the guard but 1 do not Wish to be limited thereto inasmuch as it may be varied without departing from the spirit of the invention which contemplates a movable guard yieldingly held in operativeengagement with the sai Having thus described my invention, I claim 1. A self-adjusting guard for the reinforcement of hack-saw blades, comprising, in combination, a metal member having parallel walls spaced apart and adjusted to form a frictional contact with the opposite faces of the blade, said `guard 'being yieldingly secu-red in a reinforcing position.

2. A. self-adjusting guard for hack-saw copies .of

therewith andmeans for pivotally securing ,Y

one end oflsaid guard to a stationary point.

4i. A self-adjusting guard for hack-saw blades, v comprising, in combination, av metal member U-shaped in cross-section to permit the'insertion of a saw-blade between its walls to beheld in frictional contact therewith, means for pivotally securing one end of saidguard to a'stationairy point'and frictional *means upon said'guard for pressing` against `said saw-blade in operative-proxim- Y ity to said pivotal pointfor yieldingly holding Asaid guard in place at an angle to the' longitudinal aX-is of the saw.

5. A self-adjusting guard for hack-saw blades, comprising, in combination, a rein-l forcing'member' U-'shaped vin cross section to fit over the back and :give lateral support` to the sides ofthe blade, fn'ieans'for pivotally connecting 'the same at one end to the saw, and 'means in operative lproximity* to said pivoting'means for laterally supporting the gua-rd VVin 'pivotal rotation to the blade when the forward end of the guard is raised. i

1n testimony whereof, have signed this specification in the presence of twof vsib- O `1.11-

scribing witnesses this third day gust 1918. p

Y 'RUSSELL S. '.BARNUM.

l/Vitnesses JAMEs HENDERSON, W. HARDING.

this patent may 15e-obtained for :'dve cents each, by adressingtlieWGommissioner of Taten-ts.

Washingtongn" it? 

